1. Field of the Invention
The technical field of the present invention relates to a semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
In recent years, instead of a bulk silicon wafer, integrated circuits using a silicon on insulator (SOI) substrate have been developed. By utilizing characteristics of a thin single crystal silicon layer formed over an insulating layer, transistors formed in the integrated circuit can be electrically separated from each other completely. Further, each transistor can be formed as a fully-depleted transistor, and thus a semiconductor integrated circuit with high added value such as high integration, high speed driving, and low power consumption can be realized. In the development of LSI using such an SOI substrate, improvement in the operating frequency and processing capability is realized by reducing the area of a chip by using a multilayer wiring technique.
Further, a method for forming a single crystal silicon layer over a supporting substrate made of glass by a Smart Cut (registered trademark) method has been proposed as a method for manufacturing such an SOI substrate (e.g., see Reference 1). Since a glass substrate can easily have a larger area and is less expensive than a silicon wafer, when a glass substrate is used as a base substrate, an inexpensive large-area SOI substrate can be manufactured.
[Reference]
Reference 1: Japanese Published Patent Application No. H11-163363